1. Field of the Invention
The present invention relates to a cleaning apparatus for an integrated circuit (IC) testing apparatus, and more particularly to an apparatus for cleaning probe needles of an IC electrical test apparatus and method of use thereof.
2. Description of Related Art
In the manufacture of integrated circuits (ICs), a conventional method for acceptance testing of a manufactured wafer before dicing the chips typically uses a probe card, which is mounted on a test probe apparatus. When the probe card is brought into proximity with the wafer to be tested, each one of a multitude of electrical xe2x80x9cneedlesxe2x80x9d protruding from the probe card provide a tensioned electrical contact with a unique pad (electrode) formed on the individual IC chips on the wafer.
Due to the needle pressure being applied to the probe to provide satisfactory electrical contact with an aluminum portion of each IC pad, debris and residue, such as aluminum oxide particles, are scraped/created on the surface of the wafer. Such debris and residue adhere to both the chip and the probe, and after multiple successive tests, a probe can accumulate a significant amount of such debris and residue. The accumulated debris and residue typically exhibit low conductivity and inhibit good electrical contact between the test needles and the IC pads to be tested. Thus, to provide satisfactory testing, the probe needles require periodic cleaning to remove such debris and residue from the needles.
In a conventional apparatus, a resilient abrasive pad 40 is used to clean the test probe needles. As shown in FIG. 1, the test probe 20 is inserted into the pad 40, such that any debris and residue 101 attached to the needle tips 22 are removed by abrasive particles 42 in an elastic base material 41 located in the interior of pad 40, and any remaining smaller particle (dust film) that have static attachment to the tips of the needles 20 are collected by a surface dust cover 43 as probe 20 is withdrawn from the pad 40. A significant disadvantage of such a cleaning method is that the cleaning pads 40 are expensive and must be changed frequently as they become loaded/saturated with debris particles and residue 101.
According to a preferred embodiment of the present invention, an inexpensive test probe cleaning apparatus preferably comprises a grooved silicon wafer that serves as a breaker or anvil. When the breaker is mounted in a test cradle of a test probe apparatus in a manner similar to a manufactured wafer to be tested, application of normal test probe movement and pressure by a movement controlling means causes debris and residue that may be attached to any one of the multitude of test probe needles to be crushed and abraded between the needles and the breaker. The smaller particles that result from the crushing operation fall away from the test needles and into the grooves, preferably due to the force of gravity. Although they do not create an impedance problem, any debris or residue particles that may still remain on the test probe needles may be optionally removed or blown away using a directed quantity of pressurized gas.
Unprocessed silicon wafers are the preferred choice for the breaker substrate since they are inexpensive, have a same dimension as the wafers being tested, thereby not requiring special test probe calibration for conducting a cleaning process. Further, use of wafers allows for easy creation of the grooves or ridges in the upper surface via a simple grinding operation. A preferred profile of the grooves is a saw-toothed pattern, which would allow for hard, angled surfaces that will crush any debris, but will deflect the test probe needles slightly rather than expose them to damage that may result from using an un-yielding surface.
A preferable distance from the uppermost point to the lowermost cavity of the ridged surface is in a range of 0.5 microns to 5 microns, with a distance between a first peak and a second and adjacent peak of the ridged surface being in a range of 0.1 microns to 1.0 microns. For the foregoing dimensions, a preferred displacement of the test probe coming into contact with the breaking surface is about 500 microns. The movement controlling means may comprise a displacement means, such as a motors, gears, belts, and/or levers and one or more members from the group consisting of: an optical sensor, a pressure sensor, and a displacement sensor.
A method for using such a cleaning tool may comprise: 1) placing the ridged breaking apparatus in a wafer support cradle of the IC test probe apparatus; 2) applying force to move the probe needles into contact with the surface of the ridged breaking apparatus; 3) applying a predetermined additional force to move the needles past the outermost surface of the ridged breaking apparatus, such that any debris that is attached to the end of the plurality of probe needles is broken into smaller residual portions by the crushing action of the needle movement against the ridged breaking apparatus; 4) removing the smaller residual portions from the probe needles; and 5) removing the ridged breaking apparatus from the wafer support cradle of the IC test probe apparatus. The movement of the probe tips into contact with the breaker may be in an orthogonal direction or in a direction that is at an angle between about 90 to 135 degrees, more preferably about 103 degrees, relative to the top surface of the breaker, i.e. a scraping/abrading angle.
In an alternate embodiment, a method may feature the breaking apparatus being moved relative to a plurality of stationary probe needles. Such movement may be in an orthogonal direction or in a direction that is at an angle between about 90 to about 135 degrees, more preferably about 103 degrees, relative to the top surface of the breaker.
These and other features of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.